Controllable valves for channeling or diverting a flow of fluid from one channel to another are used in many fluid flow control applications. One such application is in the field of consumer home appliances, and more particularly in modern, high efficiency washing machines. Conventional consumer washing machines utilize tremendous amounts of water during the wash and rinse cycle because all water utilized in these cycles was directly dumped overboard by a simple drain valve. However, advances in the washing machine technology and concern for conservation of natural resources has resulted in the incorporation of a controllable diverter valve in place of this simple drain valve in these new, high efficiency washing machines.
In such a machine, a solenoid actuated diverter valve is utilized to redirect the flow of water being siphoned from the washing drum so that it may be recirculated to the washing drum for a period during a particular cycle. Once this cycle of recirculation is complete, the solenoid actuated diverter valve is operated to divert or redirect the flow of water from the recirculation circuit to the drain circuit so that the water may be dumped overboard, typically to a standpipe. Such recirculation may be accomplished in either or both the wash cycle and the rinse cycle to conserve the amount of water utilized in the washing process. In a typical application for a rinse cycle, the diverter valve will first be set to a recirculation position directing any water flowing therethrough back to the washer tub. The washing machine will then begin a spin cycle, spraying the clothes with fresh water. The water is pulled through the close by the centrifugal action of the spinning tub where it falls down to the sump and flows to the water pump inlet. The pump forces the water through the diverter valve to a siphon break where it is redistributed on the spinning clothes. This recirculation is allowed to continue for a period of time. Thereafter, the diverter valve solenoid is actuated to place the diverter valve in the drain position to discharge the rinse water to the standpipe. Once all of the water used in that portion of the rinse cycle has been discharged, the solenoid is again actuated to place the diverter valve in the recirculation position so that an additional cycle may begin with fresh water. In a typical application, this process is repeated several times to completed the rinse cycle. In this way superior performance may be achieved with a significantly reduced amount of water being used.
While this high efficiency recirculation method of washing and rinsing has been perfected, the performance of the solenoid actuated diverter valves themselves have not met with such success. Because these valves rely upon a solenoid to actuate the diverter valve flipper, the physical size of this solenoid actuated valve is significant. To hold this solenoid drive mechanism in place, a large metal bracket is required. Also because of the significant weight of the solenoid and bracket, the drain bucket onto which this bracket is mounted must be made of metal to support the weight of the solenoid and bracket assembly. This further increases the overall weight of the washing machine and increases the cost per machine. Because actuation of the solenoid pulls on its armature which is connected to a lever that is attached through a shaft to the flipper of the diverter valve, the actual operation of this solenoid actuated diverter valve is also quite noisy. This noise results from the sudden contact of the armature to the housing end wall when it is pulled into position by energization of the solenoid. This loud noise several times during the wash and rinse cycles reduces the customer appeal for these washing machines, therefore adversely impacting the sales of these machines. This despite the obvious advantage of the conservation of water provided by these machines.
An additional problem existing with the usage of these solenoid actuated diverter valves is that the spring reliability within the solenoid assembly is unacceptably low. Specifically, the reliability of the spring which returns the solenoid shaft to its quiescent position when the solenoid is deenergized, returning the diverter valve flipper back to its quiescent position, is too low. As described above, a typical single rinse cycle includes several operations of a solenoid actuated diverter valve. Additionally, a typical wash cycle includes at least two rinse cycles, each of which having several actuations of the diverter valve. Further, the newest high efficiency machines are utilizing this recirculation technique during the actual wash cycles, thereby increasing the number of actuations of the solenoid diverter valve several fold.
When the typical number of loads of laundry washed by a typical family over the projected lifetime of a washing machine is multiplied by the number of solenoid actuations of the diverter valve for each complete wash cycle, it will be recognized by one skilled in the art that the reliability of the solenoid diverter valve must be significant. Unfortunately, the reliability of the springs in the typical solenoids simply does not meet these requirements. While higher reliability materials may be used to construct these solenoid springs, the higher reliability provided results in a significantly increased cost beyond which is commercially feasible in the highly competitive consumer appliance industry.
Further, the use of a solenoid driven diverter valve introduces electrical inefficiencies which significantly lessens the environmental gains introduced by the water savings. Specifically, the typical solenoid driven diverter valve uses a held type solenoid which requires the flow of electrical current through the solenoid windings during the entire period that the diverter valve is to be in the diverted position. This continuous power flow increases the users cost of ownership through increased power draw, and further introduces an additional design consideration for the product designers. Specifically, the continuous current flow through the solenoid coils introduces a heat rise which must be compensated for in the overall system design. This heat rise may limit the available materials that may be utilized to house the solenoid and its associated circuitry, and may require separate cooling considerations and/or ventilation to be added to the machine.
It is therefore a desire in the industry to have a lightweight, quiet, highly reliable diverter valve actuation system which is relatively inexpensive and which is able to control an operating pressure nearly double the deadhead pump pressure of prior designs. It is such a system that is provided by the instant invention.